Modern radio networks are realized as mobile ad-hoc networks. Ad-hoc networks do not provide an infrastructure for the transmission of voice and data traffic between the individual network subscribers. Instead, the individual network subscribers of an ad-hoc network organize the respective transmission of voice and data traffic themselves.
One quite substantial task in the organization and operation of an ad-hoc network is the time synchronization of the individual network subscribers. In this context, a frequency-hop method is used in order to prevent any disturbance of the transmission traffic. Accordingly, the carrier frequency of the transmission is modified within a given time course according to a given frequency pattern. The frequency pattern of the carrier frequency against time is known to the individual network subscribers of an ad-hoc network. To ensure that all network subscribers of an ad-hoc network switch over from one carrier frequency to the next carrier frequency of the frequency pattern at the same time, they require an identical reference time. For this purpose, a time synchronization between all of the network subscribers of the ad-hoc network is implemented within a given time grid.
A device and a method for time synchronization between the network subscribers of an ad-hoc network are known from WO 2011/154911 A1. In this context, the entire ad-hoc network is subdivided into individual groupings—so-called clusters—comprising regionally adjacent network subscribers which are positioned within the mutual transmission and/or reception range. In this case, both the transmission of payload data and also the time synchronization within a cluster are implemented through an individual transmission process (a so-called one-hop transmission). Alongside this intra-time-synchronization within the individual clusters, a time synchronization within the overall ad-hoc network is implemented via an inter-time-synchronization between respectively adjacent clusters.
In order to minimize or prevent any disturbance of the time synchronization, the continual time synchronization within one cluster is implemented in each case by alternating network subscribers of a cluster which are positioned in the transmission and/or reception range of all of the other network subscribers of the cluster. Accordingly, a typically encoded synchronization bit pattern known to all of the network subscribers of the ad-hoc network is transmitted to the other network subscribers of the cluster. The other network subscribers of the cluster accordingly synchronize their internal reference time with the internal reference time of the network subscriber transmitting the synchronization bit pattern by comparing the reception time of the synchronization bit pattern measured at their previous internal reference time, the time since the common activation of all network subscribers of the cluster measured at their previous internal reference time and the transmission time of the synchronization bit pattern stored in the synchronization bit pattern and measured at the internal reference time of the transmitting network subscriber.
In mobile ad-hoc networks, the positions of the individual network subscribers change constantly. Accordingly, for every network subscriber, the respective, regionally adjacent network subscribers of the mobile ad-hoc network, especially of the regionally adjacent network subscribers within the cluster, change over time. For this reason, the communication of the voice and/or data transmission—so-called routing—between the transmitting network subscriber and the associated receiving network subscriber in an ad-hoc network must not only be continually matched, but the composition of the cluster comprising constantly changing network subscribers and the time synchronization between the constantly changing network subscribers within a cluster must also be continually matched.
What is needed, therefore, is an approach for integrating new network subscribers into existing time-synchronized clusters of a mobile ad-hoc network and to provide the time synchronization of the network subscriber integrated into the cluster with the other network subscribers of the cluster and to provide a correspondingly designed mobile ad-hoc network.